Copper base alloy



Patented Nov. 1, 1938 UNITED STATES PATENT OFFICE COPPER BASE ALLOY Franz B. Hensel and Earl I. Larsen, Indianapolis, Ind., assignors to P. R. Mallory 8; Co., Inc., Indianapolis, Ind., a corporation of Delaware No Drawing. Application April 20, 1937, Serial No. 137,986

(Cl. 'l5160) Claims.

This invention relates to copper alloys.

An object of the invention is to produce high strength copper alloys of good electrical and thermal conductivity.

5 Another object is to improve the electrical and heat conductivities of such alloys.

Other objects of the invention will be apparent from the following description taken in connection with the appended claims.

10 Alloys of copper which are improved by adding an element having the characteristics of cobalt have been known for some time although they have never found great commercial use. One of the reasons for this is that such alloys could not 16 be produced with consistently high physical properties in the as cast condition. The alloysseem to be susceptible to intercrystalline crack- 7 ing andafter heattreatm'ent sand castings show very low tensile strength even though the hard- 20 ness might be sufliciently high. To prove satisfactory in actual service conditions it is necessary that alloys be prepared which are uniform and consistent as far as tensile, impact, fatigue and electrical properties are concerned. It was furthermore .found that the straight copper cobalt alloys when melted are extremely susceptible to temperature conditions and furnace atmosphere conditions as encountered in ordinary melting procedures. If the alloy is not very carefully prepared and melted under strictly controlled conditions the resultant-castingor forging is liable to severe cracking and therewith low tensile, impact and fatigue strength. The

' present invention contemplates the provision of Per cent Cobalt .1 to 10 Silicon l .05 t0 5 Beryllium .05 to 2.5 Copper Balance.

We have found that in the range given above Silicon Beryllium Beryllium .10 to .50

TABLE No. 1

Hardness vs. aging time (material quenched from 800' C'.)

Tun: No. 2

Conductivity vs. aging time (material quenched from-800' C.) I

' A m E m1 Time aged con fit tivity 0. Percent TABLI No. 3

Hardness vs. temperature (material aged 16 I hours at 350 C.)

Time heated alter aging Temperature 'gg 3o Alloys of the type (11). require a much higher temperature for precipitation and are about the highest temperature resisting alloys on a copper base. By adding such ingredients as silicon and cobalt, to a copper-beryllium 'alloy, the precipi- 35 tation is retarded at low temperatures and the 'strength'is still maintained after heating at a temperature or several hundred degrees above the softening point of binary copper-beryllium alloys.

The improvements in the secondary type of an alloy composed of 2.3% cobalt, .4% silicon, .25% beryllium and balance copper are illustrated in Tables 4, 5 and 6.

Turn No. 4'

45 Hardness va aaina time (material quenched from 900 0., 950 (7., and 1000 C.)

' Conductivity. aging time (material quenched 900 C'., 950 6., and 1000 C'.)

Plant conductivity ior I I material previously Tim M Aging talnquenched [mm-- 000 0. also" 0. 1,coo c. 70. C.

470 35 24 470 45 34 34 470 4B 3 40 410 us so 4s TABLE No. 6 g r I Physical properties of sand cast alloy (quenched from 950" 0., aged 16 hours at 450 0.)

Ultimate strength psi' 93,750 5 Elongationin 2" percent 10 Conductivity do 51 Hardness (Rockwell B) 98-100 As can be seen, excellent physical properties and electrical properties are obtained. 10

The improvements in the third type of an alloy composed of cobalt .51%, beryllium 28%, silicon .13%, copper balance, are given below.

A. Hardness:

Quenched from 950 C. and aged 2 hours at 400 C.: 235 Brinell B. Conductivity (completely heat treated): 47%

By comparing our new alloys as exemplified above it may be seen, with a straight coppercobalt alloy in a fully. heat-treated condition, our 2 new alloy will have a tensile strength which is at least 25,000 to 60,000 psi higher than the alloy without the silicon and beryllium. The hardness is increased at the same time by at least 100 Brinell numbers. The ratio of increase in 25 tensile properties exceeds the increase in hardness, a fact which is of extreme importance in industrial applications. It is evident that in .many castings the sections can be decreased and weight can be saved by using our new and im- 30 proved alloy. If these parts have to conduct electricity and heat this reduction in area will not hinder the current or heat flow since our new alloys have also a higher electrical and heat conductivity than the alloys previously used.

The heat treatment of the three types of alloys is slightly different. In type ('I) where a high percentage of beryllium is present somewhat. lower quenching and aging temperatures are employed than with types (II) and (III) where only a small percentage of beryllium is added. In both cases the quenching temperatures will be above 700 C. and the aging temperatures below 700 C.

The alloys may contain manganese and nickel up to .5%. Likewise the alloys may contain small proportions of other ingredients which do not materially alter their properties.

-The alloy of the present invention is suitable for a variety of electrical and other uses and particularly for electric contacting members such as resistance welding electrodes, trolley wires, trolley shoes, commutator bars and the like. The alloys having in the order of 99% copper are generally preferred where the strength and hardness is sufllcient because of their generally higher electrical. conductivity.

While the present invention as to its objects and advantages has been described herein as carried out in specific embodiments thereof, it is 30 not desired to be limited thereby, butit. is intended to cover the invention broadly within the spirit and scope of the appended claims.

What is claimed is:

1. An alloy composed of: p cent Cobalt .1 to 10 Silicon I .05to 5 Beryllium .05to 2.5

'Copper Balance 2. An alloy composed of: p cent Cobalt .3. to 1 Silicon .1" to .5 Beryllium 1.25 to 2.5 Copper Balance 18 3. An alloy composed of z Per cent Cobalt 1 to 3 Silicon .2 to 1 Beryllium .1 to .75 Copper Balance 4.1m alloy composedbf about 99% copper and- Beryllium .10 to .5

5. An electric contacting member suitable for use as resistance welding electrodes and the like formed of an alloy composed of:

characterized by the combination of high strength, high hardness and high electrical conductivity.

FRANZ R. HENSEL. EARL I. LARSEN. 

